I've taken a few, and these two are my favorites:

Learning How to Learn by Barbara Oakley: https://www.coursera.org/learn/learning-how-to-learn Hands down the biggest return on investment for an online class. It helped my future learning so much. Highly, highly recommend it.

Harvard's CS50: https://www.edx.org/course/cs50s-introduction-computer-scien... Took this course when learning to program. It was difficult, but I learned a great deal. Fantastic professor, good problem sets, and great production value.